Apparatus for controlling the pressure of furnace gases



Peb l2, A. CORBIN ETAL `APPARATUS FOR CONTROLLING THE PRESSURE 'OFFURNACE GASES 9 vSheets-$11691: 1

Filed Aug. 9, 1943 IN VENTORS FRED A Cope/N and HARRY/T NErZHAMMER,

e/f/bmeg Fell 12 1946- F. A. coRBlN ETAL APPARATUS FOR' coNTRoLLING THE.PRESSURE oF FURNACE GASES I Filed Aug. ,9, 1943 9 Sheets-Sheet 2 FRED ACORE/N ano- APPARATUS FOR CONTROLLING THE PRESSUREl F FURNACE GASESFil-ed Aug. 9, 1943 9 sheets-sheet 3 I l-:rA Feb. 12, 1946. F A CORBINIL APPARATUS FOR CONTROLLING THE PRESSURE OF FURNACE GASES Filed Aug. 9,1943 9 Sheets-Sheet 4 Feb. 12, A CORB|N ETAL APPARATUS FOR CONTROLLINQTHE PRESSURE OF FURNACE GASES Filed Aug. 9, 1945 9 Sheets-Sheet -5INVENTORS FRED ,4. Copa/N and Feb. l2, 1946. F. A. coRBlN ETAL 2,394,595

'APARATUS FORCONTROLLING THE PRESSURE OF FURNACE GASES Filed Aug. 9,1943 9'Sheets-Sheet 6 1 2 NOON 9 .mi e

INVENTORS FRED/4. Cope/N and ,HA/WWF NETZHAMMER,

Feb. -l2, 1946.

F. A. coRB'lN ErAL 2,394,595

APPARATUS FOR CONTROLLING THE PRESSURE FURNACE GASES Filed Aug. 9, 194s9 sheets-sneet '7 '.Ijg. i

11 12 NO'N 1 F. A. CORBIN, ETAL APPARATUS FOR CONTROLLING THE PRESSUREOF FURNACE GASES f Feb. 12, 1946.

File Aug. 9, 194s 9 sheets-sheet 8 INVENT RS FP50/. CORE/N and HAERVE'NETZHAMMEQ /m/bo/Wqg.

Feb. l2, 1946.

F. A. coRBlN ETAL APPARATUS FOR CONTROLLING THE PRESSURE FURNACE GASES 9sheets-sheet 9 Filed Aug. 9, 1943 Patented Feb. 12 1946 APPARATUS FORCONTROLLING THE PRESSURE 0F FURNACE GASES Fred A. Corbin, Gary, andHarry F. Netzhammer, 'Hobart Ind.

Application August 9, 1943, Serial No. 498,012

4 Claims.

In the operation of blast furnaces in the pro duction of pig iron, thegas produced during the smelting of the ore is utilized in various waysin gas consuming units disposed at various locations in the plant. Foreach long ton of -pig iron made, there are produced from 125,000 to150,000 cubic feet of top gas (reduced at atmospheric temperature andpressure). Somewhat less than onethird of this necessary for heating thehot blast stoves. A small proportion is needed for gas engines to drivethe furnace blowers, provided a cyly inder blowing engine is employed.

The remainder of the gas is available for other power purposes,including the boiler plant and the plant generating electric power fromthe gas which electricity is supplied to the blast furnace and steelmills. Also, some electricity is required for driving pumps for thecooling water.

The maintenance of uniform conditions of gas supply for the foregoinggas consumer system is an important factor in satisfactory operations.If, from any cause, as for example, increasing the volume of the windsupplied to the furnace, the volume of gas produced in a blast furnaceis increased beyond the amount consumed by the gas system, theadditional load on the gas mains and primary washers set up by suchexcess gas volume creates a back pressure on the furnaces to such anextent that the large bells of the furnaces will not open until thefurnace bleeders are opened for relief of the top pressures. Suchnecessity both disrupts the furnace operation and gas distributionthrough the gas system and creates a serious gas and dust hazard overthe plant and over wide areas around the plant.

On the other hand, deciencies in gas pressures also disrupt operation ofthe gas system, and deficiencies in the gas supply must be supple,-mented by another source of fuel, which involves the purchase andshipment of such other fuel, which is usually oil, and the use of suchat needed stations in the gas system.

In order to establish a working range between the blast furnace and theblast furnace gas consumer system, which range obviates thedisadvantages above mentioned, and other disadvantages arising from toomuch or too little gas, while establishing as low a gas main pressure aspossible and still supply suiiicient gas pressure to assure maximumoperation of the gas consumer units. This object was accomplished inaccordance with the present invention by installing automatic pressureregulators in the gas main for controlling the furnace bleeders. Suchautomatic system of regulation maintains the main pressure substantiallyconstant, thus establishing a working range between both the furnace andthe gas consumers.

The invention will be understood more readily by referring to theaccompanying drawings, wherein:

Figures 1A, 1B and 1C are veach schematic layouts of successive portionsof a typical blast furnace plant, the views taken in sequence.illustrating the complete plant, the views showing the ,locations oftheautomatic controls of the present invention; Y

Figure 2 is a diagrammatic view of a blast furnace and certain of itsassociated parts, the view showing the installation of an automaticcontrol and its location; I v

Figure 3 is an enlarged view of the automatic control shown in Figure 2.

While the invention is described and illustrated in connection with ablast furnace plant. it will be understood that it is of more generalapplication, and it is directed in its broadest asspect to an automaticgaspressure control placed in a gas main between a gas generator and gasconsuming instrumentalities whereby a predetermined gas pressure ismaintained in the line and the consuming instrumentalities are suppliedwith a constant amount of gas under the said constant predeterminedpressure. As applied to the blast furnace system, the inventioncomprises providing thel gas main from the blast furnace gas generatorwith the automatic pressure control means installed in the gas mainbetween the primary cleaners and the stoves, boiler house, and other gasconsuming installations, the pressure control means being adapted to beset at a given predetermined pressure and hold that pressure throughoutthe furnace operation, so that the gas consuming installationswillalways be supplied with a constant and adequate gas supply, excesspressures in the gas main due to excessive gas generation in the blastfurnace or furnaces being bled automatically by the automatic pressurecontrol means, subsequent to the passage of the gas under excesspressure through the con' trol means, through the bleeder stacks,opening of the bleeder valves on the furnace being almost completelyeliminated, thereby correspondingly eliminating interruption to furnaceoperation.

Referring more particularly to the drawings, there is illustrated inFigures 1A, 1B and 1C, a

''diagrammatic layout 0f atypical blast furnace plant, which isillustrated as embodying twelve blast furnaces, together with hot-blaststoves.

boiler houses. power houses, and other gas consuming installations. Inview of the self-exrenders almost entirely unnecessary any opening of4the furnace bleeder valves at any time, as contrasted with frequentopenings thereof with attendant dust and gas hazard and disruption offurnace operation. p

In the layout shown in Figures lA, 1B and 1C, the blast furnaces and gasconsumers especially No. 2 and No. 4 boiler houses were aifected byimproper gas control prior to the installation of the present automaticequipment. It may be noted in connection with the diagrams of the plantlayout, .that at the time that the gas mains and washers were installed,the blast furnaces were blowing somewhere in the neighborhood of 50,000.to 60,000 cubic feet of wind per minute, but at the present time, thedemands for increased production for the war eort have caused thefurnaces to increase their wind and the 1.000- ton furnaces haveincreased their wind as high as 94,000 cubic feet per minute, producinga cor-- responding amount of blast furnace gas. This additional load onthe gas mains and primary washers created a back pressure on thefurnaces to an extent that it was often necessary to open the furnacebleeders and relieve the top pressure before the large bells would open,creating a disruption in furnace operation and gas distribut-Zion.

As hasvbeen pointed out above, the blast fur- 24, from which the gasenters into the dust nace gas consumers, as well as the blast furnaces,

` especially No. 2 and No. 4 boiler house, were affected by improper gasregulation. In the past there was considerable range through which thepressure in the gas main could vary and still not affect blast furnaceoperation or boiler operation. 'However, under existing conditions, theboilers and gas engines'have a corresponding increased load whichparallels that of iron production. Any deficiency in blast furnace gas,due to improper pressure regulation,` musi*l be supplemented by anothersource of fuel at No. 4 boiler house. As has been noted above, thisinvolves the purchase and freight of another fuel, usually oil, for usewhile sufficient quantities of blast furnace gas are being bled into theair to enable the large bells of the furnaces to open.

As has been pointed out above, in order to esnaces and the blast furnacegas consumers, it

became imperative to establish as low' a main pressure .as possible, andstill supply suiiicient gas pressure to assure maximum boiler operation.This was accomplished by replacing the old gas main bleeder regulatorswhichA were manually operated at more or less regular intervals inacc'ordancewith the pressure of the gas in the main at the particularmoment, by automatic pressure regulators, as is described herein, whichregulators maintain the main pressure substantially constant.

Referring now to Figure 2 of the drawings. one of the blast furnaces isindicated at 20, having the usual uptakes 2l and offtakes 22 for thegas, the otakes opening into the downcomers catcher 25 and then intotheprimary washer 26.

It then passes through the cross-main 28 to the header-main 30, aportion of the gas from the cross-main being led to the stoves (notshown) through branch pipe 32. Surplus gas is led from the header-main30 to the bleederstock 34, the header-main 30 supplying gas to theboiler houses and other 'gas consuming units.

Between the header-main 30 and ythe bleeder stack 34 is a valve chamber36, into which the gas passes through line- 40 from the header-main. Theline 40 opens into the top 42 of the valve chamber 36 and gas can leavethe valve chamber 36 through line 44 and thence into the bleeder stack34.

Flow of gas lthrough valve chamber 36 trolled by a bell valve 46, thevalve 46 opening only when a gas pressure Lin excess of a predeterminedvalue 'exists in the header-main 30, such excess gas therefor passing tothe bleeder stock.

The valve 46 is controlled automatically by any one of a number ofmechanisms, that illustrated in the drawings being an example of onetype of movement relative to ports 60 and 66a in a disl tributor 64.These ports 60,'60d are connected respectively to pipes 62, 64, whichlead respectively into the upper and lower ends of a hydraulic cylinder66 in which a piston 68 operates. Piston 68 is connected to a cable 10which passes over a rocking segment l2 and thence is connected to a. rod14, this rod being tied to the bell valve 46, which is suspended fromthe rod.

The diaphragm 54 constitutes the operating member for the jet pipe, andthis diaphragm is operated by pressure transmitted to it through impulseline 5D. The diaphragm is adapted to be set for operation at any desiredpredetermined pressure, adjustment of the diaphragm .and jet pipe beingeii'ected by means of an adjusting slider 16 and adjusting screwvspring18.

The Jet pipe 58 and associated parts are enclosed in a housing 66.Hydraulic iiuid, such as oil, is introduced into the housing underpressure of a pump 82, through pipe 84 which communicates with the jetpipe 58, and returns through pipe 66 to storage receptacle 88. The pump'82 isv driven by motor 90. For indicating lpressures, a pressure gauge92 may be tapped into' the impulse line `50.

In operation, the pressure in the header-main operates through pipe 50on the diaphragm 54, which can be set to operate at any desired pressurethrough adjustment of the slider 16. When the pressure in theheader-main 30 exceeds that for which the diaphragm 54 is set, the dia,-phragm transmits such pressure, which rests on it, to the jet pipe 68through the pin 56, The

adjusting spring 18 is pushing from below. It has been tightened by theadjusting slider 16 so as to balance the power of the diaphragmat thepredetermined pressure setting so as to hold this jet pipe in neutralposition while the pressure is existing in the header-main 36.

'I'his jet pipe 58 is a pipe which is arranged to swing about ahollowand horizontal pivot. An operating liquid, which normally consists of apressure oil of about 75 lbs. per square inch of pressure, which oil isintroduced into the iet pipe through the hollow pivot to which the pipe84 is connected, the oil being forced therethrough under pressure of thepump 82. This pressure oil streams through the jet pipe and it leaves itthrough the nozzle with full energy. In the housing B0, facing thenozzle of the jet pipe, are the two closely adjacent orices 60 and 60a,which orices are f the inside diameter of the nozzle, both of whichorifices are connected by pipes 62 and 64 with the cylinder 66 on bothsides of the piston 68. In the central position of the jet pipe, whichis the neutral position, the oil stream from the nozzle strikes equallyon both orifices.

Now, if the gas pressure in the header-main 30 increases above theadjusted valve on account of a stronger supply or of a smallerconsumption of gas, the pressure of the diaphragm 54 will becomecorrespondingly stronger and it will outweight the pressure of thespring 18. The spring consequently is'pressed together, and the jetpipe, which is between the push-pin 56 and the spring, will be moveddownwardly as viewed in Figure 3, and the movement will be so much themore, the stronger the increase of the gas pressure becomes. Thus, theoil stream strikes more and more, on the orifice 60a., so that-the oilpressure in the pipe 64 increases proportionally and decreases in pipe62. The piston 68 therefore is caused to rise, and the segment 12 rocksunder the released weight of the valve 46 and bar 14, so that. the valveis lowered from its seat 94 and pipes 40 and 44, are thus brought intocommunication, and the excess gas allowed to bleed through stack 34, itbeing burned at the top of this stack.

Thus, the equilibrium between supply and consumption of the gas isrestored again and the force of the adiustng spring can push the jetpipe 58 back again. In that instantwhen the gas pressure in the line 30is equal to the predetermined set valve of the control mechanism, thejet pipe 58 will finditself in its centra] position and the oil streamstrikes equally again on the orifices 60 and 60a. Then pressure on bothsides of the piston thus is equally strong and the new position of thepiston remains fixed until the pressure in the header-main drops belowthe pressure setting of the control. at which instant the reverseoperations take place and the jet pipe comes onnosite to the orifice 60,causing the piston 6B to pull the valve 46 to its closed position.

As is shown in Figures 1A, 1B, and 1C, the illustrated plant layout isprovided with three of these automatic controls, namely, adjacent to No.1 bleeder stack. No. 2 bleeder stack, and No. 3 bleeder stack. Beforeinstallation of the automatic control on No. 1 bleeder stack, the gaspressure varied from a low of ve inches of Water to a high oftwenty-three inches of water pressure. After installation-of thecontrols, it is found in practice that the pressure is maintainedconstantly at seventeen inches of water, or whatever pressure isdesired, depending on the variation in operation.

The gas pressure in the header-main near No. 2 and No. 3 bleeder stacksbefore and after installation of the controls, is similar to No. lexcept that the control pressure is set to maintain the pressurenecessary for proper distribution of vgas to consumers served in thisarea.

The regulated gas bleeding not only controls the gas pressure throughoutthe mains, but helps to determine the supply of gas available for thevarious consumer units. It also affords means the gas bled anddistributed throughout the entire blast furnace gas system and to beable to control and determine the supply of fuel results in a moreeilicient and greater application of it.

In addition to the foregoing, the installation of the automatic controlsnot only holds the gas pressures at the top of the furnace to within arange permitting bell operation, but it is found in practice that analmost uniform tcp pressure is being maintained. Prior to theinstallation of the automatic controls nof'definite top pressure trendcould be noted, but sincev the installation of the automatic controls, adenite trend is established towards a uniform top pressure.

Also, results obtained in practice show definitely that the gas pressureregulation reiiects back through the furnace and results in a moreconstant blast pressure to the furnace. Since this is reflected backthrough the burden, there is little doubt but what furnace operation hasbeen greatly improved andthe slipping of the burden vastly reduced.

Also, the load on the blowing engines has been reduced and more air isbeing delivered to the furnaces due to controlling the erratic furnacetop pressure. Likewise, the opening of the bleeders 96 on top of thefurnace in order to relieve the excessive pressure hindering the openingof the bells has been almost entirely eliminated. This means that thedust and ore that was being blown out 0f these bleeders and causing ahazard to the plant and community, has been eliminated, as well as thedetrimental eilect on machinery and equipment.

The high top pressures formerly encountered were continually causing thelarge bells to hang, thereby requiring constant vigilance to prevent thebreaking of bell cylinders and liners. has been eliminated by thepresent invention. Also, the blowing of auxiliary seals that sometimeswere not capable of absorbing the high pressures resulting from furnaceslips, has'been relieved," as well as the necessity of maintaining largelabor crews in cleaning up accumulated ore' dust in the plant yard andin cleaning the furnace tops, which was required to be done continually,this labor now being diverted to advantageous use elsewhere.Furthermore, a very great improvement in the reduction of dirtaccumulation in the mains of the blast furnace gas system has resultedfrom the present invention.

Many other advantages are present thrceuglri-V Y out the p-lant becauseof the improvements of the present invention. Thus, the controlledpressure of gas to the washers results in a steady and uniform volume ofgas flowing through the washers, thereby improving the e'iciency of thewashers. Before the controls were installed, it was impossible tomaintain a steady flow through the washers. A variation in flow from10,000 to 20.000 cubic feet per minute was not unusual. With thecontrols installed, the flow is maintained constantly at 15,000 cubicfeet per minute. Prior to the installation of the controls, dailyanalysis of the gas showed a dust content of 0.012 to 0.021 grain percubic foot. Since the controls have been installed, it has been showingapproximately 0.010 grain per cubic foot daily, with the exception dueto overloading of the washers on account of too many being shut down forcleaning orA repairs.

Also, improved stove operation is effected by the present invention. Itis a well established fact that one of the rst steps in good gas com-This bustion is the regulation of the sas pressure, certain of thestoves for the furnaces illustrated in Figures 1A. 1B and 1C haveinspirating burners,

' a constant gas flow inspirates air far Vmore satisfactorily than a.surging gas supply. Analysis of the gas taken before the controls wereused indicated very poor combustion and frequent adjustments of theburners were necessary in order to obtain eiliclent combustion of thegas. Since the installation of the controls, eilicient combustion can bemaintained with infrequent burner adjustments. Furthermore. all thestoves have a tendency to set up a pufling condition resulting from .gassurges. With the controls and with a proper setting ofthe burners, thistendency is eliminated, and a smooth eicient flame now is attained. v

The foregoing are a few of the advantages of the present invention. Verysubstantial savings in equipment, materials and money are effected bythe automatic controls of the present invention, whichsavings extendthroughout the entire plant.

We claim: 1. A blastfurnace system comprising, in combination, aplurality of blast furnaces, a gas main connected to theblast'furnaces', instrumentalities.' interconnected with the gas mainfor utilizing gases produced in the furnaces, a plurality of gasbleeders connected to the gas main for relieving gas pressure thereinabove 4a predetermined'constant pressure, and gas pressure controlmechanisms intermediate the furnaces and each bleeder, each-mechanismincluding control valve means disposed intermediate its bleeder and thegas main supplying gasto the said gasutilizirig instrumentalities,andoperating mechanism for the valve means automatically operableresponsively to deviations in gas pressures in the system from the saidpredetermined constant from the said constant pressure in selectedstations in the system for continuously maintaining the said pressuresubstantially constant throughout the system, thereby maintaining aconstant supply of gas to the said gas-consuming instrumentalitiesindependently of variable operating conditions in any of the saidfurnaces. v

3. A blast furnace plant comprising, in combination, a plurality ofblast furnaces, a gas main adapted to receive blast furnace -gas fromthe furnaces, a plurality of gas-consuming stations connected to the gasmain for receiving and utilizing blast furnace gas from the said gasmain, the said gas-consuming stations being at various remote distancesfrom the blast furnaces, a plurality of gas bleeders connected to themain at selected spaced locations adapted to relieve excess gaspressures inv selected portions of the main. and gas pressure` controlmechanisms intermediate the gas main and each bleeder, eachof thecontrol mechanisms including control valve means adapted to controlpassage of gas fromA the gas main to the bleeders, and operatingmechanism for the valve means automatically operable responsively todeviations in gas pressures in the gas main from a predetermined valuefor maintaining the gas pressure constant throughout the gas main at thesaid predetermined value, thereby maintaining aconstant supply of gas toall of the gas-utilizing stations independently ofl j variableconditionsof operation in any particular furnace and irrespectively ofthe distance of the gas utilizing stations from the said blast furnaces.

4. A blast -furnace plant comprising, in combination, a plurality ofblast furnaces, a gas main adaptedv to receive blast furnace gas fromthe y furnaces, connections between the furnaces and pressure inselected stations' in the system for maintaining' the gas pressurethroughout the system` continuously substantially constant at the saidpredetermined value, thereby maintaininga lconstant'supply vof gas to.the gas-utilizing in. strumentalities independently o f A variable con-A ditions of operation in any particular furnace.

2l A blast furnace s'ystem'comprising, in combination, abattery of blastfurnaces, each furnace of which battery is delivering gas at differingVand varying rates, a gas main common to the said furnaces for receivinggas therefrom, instrumentalities connected to the said gas main forconsuming thev gas produced in the furnaces,

means for receiving the gas-delivered from the furnaces at the saiddiffering and varyingrates and for-supplying the said gas to thegas-consuming instrumentalities in a steady iiow ata constant pressure,a plurality of bleeders distributed in the system intermediate thefurnaces and gasconsuming instrumentalities, and .gas pressure lcontrolmechanism for each bleeder, the said mechanism including means operableresponsively to deviations in gas pressures in the system the said gasmain, a plurality of gas-consuming Istations connected to the gas mainfor receiving and utilizing blast furnace gas from the said gas main,the said gas-consuming stations being at various remote distances fromthe blast furnaces,

' and means for maintaining a predetermined constant pressure 'of gasthroughout the gas main and gas-consuming stations, the said meansincluding bleeder instrumentalities for bleeding excess gas pressurefrom the gas main to the atmosphere and control mechanisms intermediatethe gas main and bleeder instrumentalities, the said lcontrol mechanismsincluding control valves adapted to control passage of gas from the gasVmain to the bleeder instrumentalities, and operating mechanism forthevalves automatically operable responsively to deviations in gaspressures in the gas main from the said predetermined constant pressure,thereby maintaining a constant supply of gas toall of the gas-utilizingstations independently of variable conditions of operation in anyparticular furnace and irrespectively of the distanceof the gasutilizing stations from the said blast furnaces.

`FRED A. CORBIN. HARRY F. NETZHAMMER.

